1. Field of the Invention
The present invention relates generally to propeller-type fans for displacing fluids. In another aspect, the invention concerns an energy efficient, quiet, and aesthetically pleasing fan having a propeller directly coupled to a drive shaft of the fan motor.
2. Description of the Prior Art
Most conventional propeller-type fans, especially air circulators, are produced without regard for controlling the air flow past the fan motor. Usually the motor is left exposed in the air stream where it contributes significantly to the aerodynamic drag of the fan system and adversely affects air flow. The adverse air flow is characterized as turbulent air flow that contributes to reduced operating efficiency, poor motor cooling, and increased operating noise. The exposed motor offers poor aesthetic appeal in applications where styling is of economical importance. Further, if the exposed motor becomes hot during operation, its outer surface could cause discomfort or even burns if touched by a human.
It is, therefore, an object of the present invention to provide a propeller-type fan having an enhanced aerodynamic configuration that minimizes turbulence of the air flowing past the fan motor.
A further object of the invention is to provide a propeller-type fan having enhanced energy efficiency.
A still further object of the present invention is to provide a propeller-type fan having reduced noise output.
A yet further object of the invention is to provide a more streamlined and aesthetically pleasing propeller-type fan.
Another object of the invention is to provide a propeller-type fan which provides for enhanced cooling of the fan motor.
Still another object of the invention is to provide a propeller-type fan having a cover over the fan motor to reduce the risk of human injury due to physical contact with a hot outer surface of the motor.
Yet another object of the invention is to provide a system for enhancing the efficiency of a propeller-type fan by separating the air flowing past the fan motor into a cooling air stream which passes over the motor and a general air stream which is separated from the motor.
It should be understood that the above-listed objects are only exemplary, and not all the objects listed above need be accomplished by the invention described and claimed herein.
Accordingly, in one embodiment of the present invention, there is provided a fan comprising a motor housing and a motor shroud. The motor housing presents an axially extending outer sidewall surface. The motor shroud is radially spaced from the outer sidewall surface and surrounds at least a portion of the outer sidewall surface. The motor shroud presents inner and outer shroud surfaces. The inner shroud surface and outer sidewall surface define an axially extending cooling air passageway therebetween.
In another embodiment of the present invention, there is provided a fan comprising a motor, a drive shaft, a fan blade assembly, a spinner, a distributor core, and a motor shroud. The motor includes a housing having first and second axially spaced end walls and a sidewall extending between the end walls. The drive shaft is rotatable on a motor axis and is powered by the motor. The drive shaft extends out of the motor through the first end wall. The fan blade assembly includes a hub which is rigidly coupled to the drive shaft. The spinner is rigidly coupled to the drive shaft and at least partly covers the hub. The spinner presents a substantially smooth outer spinner surface having a rounded spinner end portion. The distributor core is rigidly coupled to the motor proximate the second end wall. The distributor core presents a substantially smooth outer core surface having a rounded core end portion. The motor shroud is radially spaced from and surrounds at least a portion of the sidewall.
In a further embodiment of the present invention, there is provided a method for circulating air. The method comprises the steps of: (a) rotating a fan blade assembly to thereby force air to flow past a motor which provides power for rotating the fan blade assembly; and (b) separating the air flowing past the motor into a cooling air flow and a general air flow, said cooling air flow flowing between an outer sidewall surface of the motor and an inner shroud surface of a motor shroud surrounding the motor, said general air flow flowing outside an outer shroud surface of the motor shroud.